A conventionally used spark plug has a noble metal tip provided at a distal end portion of an electrode. Manufacturing such a spark plug usually employs the following processes: a composite tip is formed by joining a noble metal tip to an intermediate tip (e.g., an Ni tip), and the intermediate tip of the composite tip is joined to a distal end portion of an electrode.
However, since the noble metal tip and the intermediate tip are such small members as to have a diameter of about 1 mm or so, forming the composite tip by joining the two members together has encountered difficulty in correctly setting up the relative positional relationship therebetween. Also, for example, in manually positioning the noble metal tip and the intermediate tip, the positional adjustment has consumed time. Such problems do not exclusively arise in a process of joining the noble metal tip to the intermediate tip, but have generally arisen in attempting to correctly set up the relative positional relationship between two tips before joining them together. Also, similar problems have arisen in joining a tip, such as a noble metal tip, directly to a center electrode or a ground electrode.